Glossary of Terms

We know that many of the concepts used on this site can be difficult to understand. For that reason, we have provided you with a glossary to help you make sense of the terms used in Comparative Effectiveness Research. Every word that is defined in this glossary should appear highlighted throughout the Web site. When you come upon a highlighted term and would like to read the full definition, you can either click on the word to visit the glossary or roll your mouse over the word for a pop-up definition.

Definition: A study of two drugs or treatments that compares the effects of one treatment with the other. In a head-to-head trial, two groups of people with the same disease are compared. One group receives one treatment, and the second group receives the other.

Example: For example, a clinical trial that compares people treated with aspirin to people treated with salsalate for osteoarthritis pain is a head-to-head trial.